In the last run of Flanger PCBs, there is a resistor space labelled 47k. It should be 1K. This is the feedback limiting resistor. 47k is too high and gives a very weak or almost no feedback at all. Sorry for any confusion and/or frustration. The good news is that it's a very simple fix.
The only confusing part is whether or not you have one of the PCBs that needs this change. If you have one of the flangers from the first run of Rev1.0 PCBs, you do not need to change anything. Everything is labelled correctly. You'll know you have a first run flanger because it will say "BETA" on it, even though it's not a BETA board (we forgot to remove that when we went to production). BETA will be printed vertically along side the 1N4001 diode at the top center of the PCB near the off board wiring eyelets for the DC adaptor jack.
If your PCB says REV1.0 with the word BETA on it, or if you have a newer REV1.1 or higher, then you don't need to worry about this. If you're at all confused by this, just build it according to the instructions. This isn't a major fix. When you're done, if you've got a great sounding chorus pedal, but the REGEN knob isn't giving you any sort of flange-like feedback, then you probably need to change the 47k resistor to a 1k.
If you've got a Flanger pedal that just has problems and isn't doing anything at all or isn't giving you a proper chorus effect DO NOT EVEN CONCERN YOURSELF WITH THIS!!!!! THIS PROBLEM IS VERY MINOR AND WOULD NOT AFFECT ANYTHING OTHER THAN THE REGEN KNOB!!!!